Despite solid quarterly results, Netflix's (NFLX 1.03%) stock fell more than 4% on Tuesday. Netflix brought in 630,000 new U.S. subscribers, but some analysts raised concerns about the rising cost of original content. In our lead story on Investor Beat, Motley Fool analysts Jason Moser and Bryan Hinmon examine the amazing run Netflix's stock has had over the past year, the challenge of turning out more original hit shows, and what it all means for investors.